There is not really any "labour force" in the game, as you would think. It is all abstract. The reason why you experience labour shortages is because of your inflation. You get a high inflation when your GDP\c grows at a higher rate than your economy can handle. The reason this happens is because your are putting too much money into your economy and thus you need to reduce your expenses to reduce GDP\c growth thus inflation. This is not so complicated, once you know how the economy model works. I adcvice the following when you try to expand your industries.

1. Be patient. Do not build more than your economy can handle at once.
2. Reduce social spendings and\or increase taxes when you are constructing buildings. This will lead to a slower GDP\c growth (because less money is inserted into your economy) and you will be able to expand your economy faster. I usually lower or even totally shut off social security, environmental spending and cultural spending when I see that my inflation is getting out of hand. I also manually control both taxes, social spending and consumer goods and other products that are consumed (oil, electricity) in addition to military goods and industry goods.
3. Do not overproduce units. It is easy to build a lot of military construction fabs, and not realise how they will affect your economy. When you build units they add very little to your economy (from my experience) and thus they are a direct expense you do not get a return on. Balancing your budget may prove difficult when you produce a lot of buildings and units at once.